From 91d4c835ad937024abf2e5c71099819098ea0009 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 14 Apr 2022 12:55:33 +0200
Subject: [PATCH 1/3] Introduce `TabMap::line_len`

---
 crates/editor/src/display_map/tab_map.rs | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/crates/editor/src/display_map/tab_map.rs b/crates/editor/src/display_map/tab_map.rs
index 77ec73d8bf8b3cb8d2e116b401155634efcdc62f..1491c790f60229e68ec86f1b967a157a51378b43 100644
--- a/crates/editor/src/display_map/tab_map.rs
+++ b/crates/editor/src/display_map/tab_map.rs
@@ -96,6 +96,22 @@ impl TabSnapshot {
         self.fold_snapshot.buffer_snapshot()
     }
 
+    pub fn line_len(&self, row: u32) -> u32 {
+        let max_point = self.max_point();
+        if row < max_point.row() {
+            self.chunks(
+                TabPoint::new(row, 0)..TabPoint::new(row + 1, 0),
+                false,
+                None,
+            )
+            .map(|chunk| chunk.text.len() as u32)
+            .sum::<u32>()
+                - 1
+        } else {
+            max_point.column()
+        }
+    }
+
     pub fn text_summary(&self) -> TextSummary {
         self.text_summary_for_range(TabPoint::zero()..self.max_point())
     }
@@ -517,8 +533,11 @@ mod tests {
                 actual_summary.longest_row = expected_summary.longest_row;
                 actual_summary.longest_row_chars = expected_summary.longest_row_chars;
             }
+            assert_eq!(actual_summary, expected_summary);
+        }
 
-            assert_eq!(actual_summary, expected_summary,);
+        for row in 0..=text.max_point().row {
+            assert_eq!(tabs_snapshot.line_len(row), text.line_len(row));
         }
     }
 }

From 1a1d67010400c28a25d0e04b79a6244dca6c35a7 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 14 Apr 2022 13:01:29 +0200
Subject: [PATCH 2/3] Speed up `WrapSnapshot::line_len` using the indexed
 transforms

---
 crates/editor/src/display_map/wrap_map.rs | 28 +++++++++++++++++------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/crates/editor/src/display_map/wrap_map.rs b/crates/editor/src/display_map/wrap_map.rs
index 00e9b63b1ad66625942c62daf21c4b04c372bb9f..be356044f8b573c13ae0d6614f30cea33af22228 100644
--- a/crates/editor/src/display_map/wrap_map.rs
+++ b/crates/editor/src/display_map/wrap_map.rs
@@ -599,16 +599,23 @@ impl WrapSnapshot {
     }
 
     pub fn line_len(&self, row: u32) -> u32 {
-        let mut len = 0;
-        for chunk in self.text_chunks(row) {
-            if let Some(newline_ix) = chunk.find('\n') {
-                len += newline_ix;
-                break;
+        let mut cursor = self.transforms.cursor::<(WrapPoint, TabPoint)>();
+        cursor.seek(&WrapPoint::new(row + 1, 0), Bias::Left, &());
+        if cursor
+            .item()
+            .map_or(false, |transform| transform.is_isomorphic())
+        {
+            let overshoot = row - cursor.start().0.row();
+            let tab_row = cursor.start().1.row() + overshoot;
+            let tab_line_len = self.tab_snapshot.line_len(tab_row);
+            if overshoot == 0 {
+                cursor.start().0.column() + (tab_line_len - cursor.start().1.column())
             } else {
-                len += chunk.len();
+                tab_line_len
             }
+        } else {
+            cursor.start().0.column()
         }
-        len as u32
     }
 
     pub fn soft_wrap_indent(&self, row: u32) -> Option<u32> {
@@ -741,6 +748,7 @@ impl WrapSnapshot {
                 }
             }
 
+            let text = language::Rope::from(self.text().as_str());
             let input_buffer_rows = self.buffer_snapshot().buffer_rows(0).collect::<Vec<_>>();
             let mut expected_buffer_rows = Vec::new();
             let mut prev_tab_row = 0;
@@ -754,6 +762,8 @@ impl WrapSnapshot {
                     expected_buffer_rows.push(input_buffer_rows[buffer_point.row as usize]);
                     prev_tab_row = tab_point.row();
                 }
+
+                assert_eq!(self.line_len(display_row), text.line_len(display_row));
             }
 
             for start_display_row in 0..expected_buffer_rows.len() {
@@ -957,6 +967,10 @@ impl WrapPoint {
         &mut self.0.row
     }
 
+    pub fn column(self) -> u32 {
+        self.0.column
+    }
+
     pub fn column_mut(&mut self) -> &mut u32 {
         &mut self.0.column
     }

From 6d33697e82e9a55355b7e643d1e3022d2caa614c Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 14 Apr 2022 13:03:46 +0200
Subject: [PATCH 3/3] Fix warning

---
 crates/editor/src/display_map/wrap_map.rs | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/crates/editor/src/display_map/wrap_map.rs b/crates/editor/src/display_map/wrap_map.rs
index be356044f8b573c13ae0d6614f30cea33af22228..0e88d87bd77b06ff3a4ab8bfb49c7f0c1aa2433e 100644
--- a/crates/editor/src/display_map/wrap_map.rs
+++ b/crates/editor/src/display_map/wrap_map.rs
@@ -559,11 +559,6 @@ impl WrapSnapshot {
         Patch::new(wrap_edits)
     }
 
-    pub fn text_chunks(&self, wrap_row: u32) -> impl Iterator<Item = &str> {
-        self.chunks(wrap_row..self.max_point().row() + 1, false, None)
-            .map(|h| h.text)
-    }
-
     pub fn chunks<'a>(
         &'a self,
         rows: Range<u32>,
@@ -1286,6 +1281,11 @@ mod tests {
             self.text_chunks(0).collect()
         }
 
+        pub fn text_chunks(&self, wrap_row: u32) -> impl Iterator<Item = &str> {
+            self.chunks(wrap_row..self.max_point().row() + 1, false, None)
+                .map(|h| h.text)
+        }
+
         fn verify_chunks(&mut self, rng: &mut impl Rng) {
             for _ in 0..5 {
                 let mut end_row = rng.gen_range(0..=self.max_point().row());